Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
Intelligent UPS System for Smart Grid to Achieve the
Sustainable Energy
Ravi Angadi1
PG-Scholar, Department of
Electrical and Electronics
Engineering,
KEC Kuppam, JNTU
Anantapur, AP, India
S. Zabiullah2
Asst. Professor, Department of
Electrical and Electronics
Engineering,
KEC Kuppam, JNTU
Anantapur, AP, India
Ch. Jayavardhana Rao3
Associate. Professor, Department
of Electrical and Electronics
Engineering,
KEC Kuppam, JNTU
Anantapur, AP, India
ABSTRACT
The modern area trend technology completely depends on the continuous power supply and the
economic growth of the nation is completely depending upon the availability of the power supply. To
achieve these parameters like voltage, current and frequency of the power system should be at
rated values, because of remote generation, transmission and distribution we are failing to receive
the reliable power. . In view of this we are proposing intelligent uninterruptible power supplies
(UPS) for smart grid to achieve the sustainable energy which operates in multi- functional modular,
intelligent UPS system for smart grid consists of four identical H-bridge converters. The intelligent
UPS controlling is achieved with the help of SPWM techniques, also not only can realize all the
basic functions of the traditional on- line UPS system, but also can gives pictorial path for the cyclic
use of the electrical power between the power grid and storage battery. In the proposed system also
we can easily interface the renewable energy sources in order to achieve the sustainable energy.
Moreover, due to the modular design, it can easily operate in any power converters mode for any
applications. The configuration and working principle of the proposed IUPS system are analyzed,
and controlling is achieved by designing and modeling of intelligent UPS system and results are
verified with the help of MAT LAB/Simulink.
Keywords
Converter/ Inverter, intelligent UPS, SPWM, Renewable energy source.
INTRODUCTION
In order to achieve the continuous power supply existing UPS power supply no longer safe and not
satisfies the demand days are becoming more and more smarter also the demand of electricity also
increasing so to over coming this smart grid took place but how longer alone it will be fulfill the
demands so in view of this here we are proposing a n intelligent UPS system for smart grid which
will be works as backup to the system and also fulfill the demands [2].
Intelligent UPS is designed such way; it will operate in the different multifunctional modes
according the necessary conditions. This system is entirely separate from other UPS system it
doesn’t have any transformer and which will make a system simpler and more effective and less cost.
In the mean time we can easily interface the renewable energy sources/ distributed generation [4].
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Ravi Angadi, S. Zabiullah, Ch. Jayavardhana Rao
Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
This proposed system will not only draws the supply from the source but also it will fed back to the
grid or utility when ample amount of sources are available at the battery storage.
Transformer-based units integrate passive magnetic with fewer active power conversion components
resulting in a simpler manner [1]. In choosing between transformer-based and transformer- free
uninterruptable power supply system and designer should be understood that where the transformer
are best utilized and whether they should be internal and/or external to the UPS in view of physical
and electrical distribution requirements and tradeoffs [3]. In mean tine easily interface renewable
energy sources
INTELLIGENT UPS FOR SMART GRID
The techniques and tradeoffs utilized in the different rectifier unit, storage unit, inverter unit and the
bypass functions of these two UPS designs for various UPS system performance functions. Site
Planning and Adaptability Many users find that transformer- free UPS equipment provides greater
flexibility in accommodating uncertain future requirements
Fig.1. Intelligent UPS for Smart Grid
Transformer- free designs are usually smaller in size than an equally power-rated transformer-based
design, providing opportunities to locate the UPS physically closer to the point of power usage or on
a more lightly rated (pounds/sq. ft.) raised floor [5]. Applying a transformer- free UPS to a critical
power distribution system does not mean that all tra nsformers in the power path can be eliminated,
but does allow the system designer to place transformers only where they are needed. The above
fig.1 shows the pictorial representation of Intelligent UPS for Smart Grid.
Once it is determined where transformers may be needed in the system, transformer- free UPSs may
permit more optimal placement in the power distribution path. However, it must be remembered that
transformer-based UPSs have some of these functions internally integrated as part of the system
design, a potential reliability benefit. Reliability and Availability Transformer-based UPSs have an
inherently higher reliability due to a much lower parts count, robust redundant. All major UPS
59 Ravi Angadi, S. Zabiullah, Ch. Jayavardhana Rao
Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
manufacturers produce both topologies for mission critical applications to accommodate UPS system
designer preferences. Transformer-based UPS units utilize a combination of passive and active fault
diagnosis systems, transformerless systems is designed [7]. The control strategies a nd expanded
power conversion processes within the SPWM rectifier, DC/DC converter and inverter of the
transformer-free UPS power supply.
DESIGN AND ANALYSIS OF IUPS SYSTEM
The smart grid plays a very important role now days to meet the demands of the cons umer. In order
to make this smart grid more smart and smarter the single use of online UPS system no longer
satisfies so to overcome this and make smart grid success the transformer- less Intelligent UPS
suggesting by this paper which will be operating very smartly according to the necessary conditions.
The below fig.2 shows the constructional design of transformer less IUPS for smart grid.
Fig.2. Structure of Intelligent UPS for Smart Grid
The main theme of the IUPS is to provide the clean and continuous source and acceptable power to
the load irrespective of the source. It consists of 4- identical H-Bridge bidirectional
converter/inverter station [10]-[11]; they are named as station H1, H2, H3and H4 converter station.
The controlling action is achieved by with the help of SPWM technique in order to get the pure sine
wave [8]. This technique is characterised by constant amplitude pulses with different duty cycle for
each period and the width of the pulses are modulated to get inverter output voltage control and also
it will reduces the harmonic value. In SPWM technique a sinusoidal modulating signal is compared
with a switching frequency triangular waveform to generate the switching signal for the inverter
devices, by changing the control signal magnitude the width of the gate drive for the devices can be
varied and hence output voltage magnitude is also varied also by changing the frequency of the
modulating wave the fundamental frequency at the inverter output changes.
60 Ravi Angadi, S. Zabiullah, Ch. Jayavardhana Rao
Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
In general terms, robustness is an expression of a qualitative level of abuse that an online UPS
system can handle beyond its 0-to-100 percent ratings while still meeting its availability
requirements [7]. Both transformer- free and transformer-based UPS can provide excellent and
similar dynamic overload capabilities for phase-to neutral or three-phase dynamic load events.
These units provide automatic handling of temporary overloads and faults on the downstream
distribution network and can provide on-the-fly paralleling with the AC bypass in support of
overload and load fault management. Transformer-based UPSs add the benefit of some degree of
passive fault handling through internal transformers and filters. Most transformer-based designs use
circuit breakers at key disconnect points (Input, Output, Bypass and Battery). These circuit breakers
provide over-current protection and allow for greater fault clearing capabilities.
Some transformer- free designs may use a contactor and fuse combination which can present
problems during certain overload or fault conditions. Specifically, an inverter IGBT can fail short
which may cause the contactor to weld and introduce a DC current onto the bus along with this most
of the contactors will be unable to open during DC fault conditions or high, AC fault current
situations which could be easily handled by a properly sized circuit breaker. Also, in a transformerbased UPS, the DC fault current cannot pass through an isolation transformer. As a result, the input
feeder or the critical bus cannot experience any DC fault conditions, or cascading DC faults.
OPERATION OF PROPOSED IUPS
As name it indicates that intelligent UPS it will be operating in the different multifunctional modes
according to the necessary condition it will totally operating in the following modes as follows
IUPS Mode-1: Static by Pass Power supply Mode:
When the UPS is under in malfunction condition the grid supply will be directly fed to the load via
the static by pass switch which leads continues power supply, under this condition the
converter/inverter station H-1, H-2, H-3 & H-4 will not come into action.
IUPS Mode-I1: UPS- Powe r supply Mode:
In the UPS power supply mode, the static by pass switch will not come into action and all
converter/inverter station will starts working and in this mode station H-1 will be working as a
converter which will converts the ac-dc and mean time it will be connected to load via H-2 inverter
station. The energy stored in the battery through converting ac-dc-ac-dc under this case converter
stations H-3 & H-4 will come into picture and supply the energy in the battery bank.
IUPS Mode-III: Batte ry - Power s upply Mode:
During the failure of the grid supply this battery power supply will come into action and it will fulfill
the demand of the consumer. Under this case the H-3 and H-4 and H-2 will come into action it will
convert dc-ac-dc-ac then it will be connected and fulfill the demand under the power grid source
failure case.
IUPS Mode-1V: Battery – Feed powe r supply Mode:
During in this case the demand of the load less and the energy stored in the battery is ample due to
the interfacing of the renewable energy generation can be feed it back to the grid by converting into
dc-ac-dc-ac the to grid under this case utility grid will be act as a load the battery under this
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Ravi Angadi, S. Zabiullah, Ch. Jayavardhana Rao
Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
converter station H-4, H-3 and H-1 will be come into picture. So by this we can support the smart
grid to become success in the future [9] [12].
IUPS Mode-1V: Battery – Feed powe r supply via static bypass switch if H-1 Failure Mode:
Under this mode if the converter station H-1 fails and it’s not possible to send the sources to load but
we have battery power supply mode, we can feed the load without interrupting, in the me antime if
grid requires a sources to full fill the other load that time, we can easily feed the grid by battery
source any way here we are interfacing the renewable energy source we can also easily support grid
to make more smarter.
IUPS Mode-V: Battery s upply mode and UPS powe r supply mode if Converte r station H-3 fails
mode:
Under this mode it will be perform 3 additional functional according to the necessary conditions
firstly it will feed the load via H-4, H-1 & H-2 converter station, secondly UPS power supply mode it
will feed the load via H-1 & H-2 and as well as charge the battery via H-3 and thirdly it will also
works in static by pass mode via H-4 station totally it will check the condition’s according it will
turns on the particular mode of operation and will be continuously feed load if necessary or it will
feed the grid when it requires. So this we can make smarter intelligent UPS system.
SIMULINK MODEL OF IUPS
The Intelligent UPS is designed by using Matlab Simulink toll and constructed according to the
proposed work the below fig.3 shows the basic model of IUPS which consists of two parts firstly is
Controller part and the second one is UPS system. The IUPS will operating in the different modes
that can be controlled by using SPWM technique to generate the pulses for converter station
according to in which made necessary by giving a feedback signals to the controller and which will
be generates the pulses by comparing with the reference signals and gives the pulses to bridge which
is shown in the fig.4. & 5 below;
Fig.3. Intelligent UPS for Smart Grid
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Ravi Angadi, S. Zabiullah, Ch. Jayavardhana Rao
Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
Fig.4. Control structure of IUPS for Smart Grid
Fig.5. Pulse generator for bridges by SPWM
Fig.6. Simulink Model of Intelligent UPS for Smart Grid
The above fig.6. Shows the final modeling of Intelligent UPS system for smart grid. By constructing
this we can easily make the system to be operate in different modular according to the necessary
condition , also we can easily achieve the online UPS for both the load and as well grid connecting if
grid requires additional sources in order to meet the demand of the other load which connected to
grid.
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Ravi Angadi, S. Zabiullah, Ch. Jayavardhana Rao
Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
SIMULLINK RESULTS OF IUPS SYSTEM
The modeling of the IUPS has been done and the different modes of operation simulation results are
expressed below.
Figure 7. Input source voltage from grid
Figure.9. Load current and voltage During UPS mode .
Figure.11. DC Link BUS Voltage
64
Figure.8. Static by pass power supply mode
Figure.10. Load current and voltage during battery power supply mode
Figure.12.Battery feed power supply mode
Ravi Angadi, S. Zabiullah, Ch. Jayavardhana Rao
Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
Figure.13. Battery power feed & Battery supply
mode if H-3 failure.
Figure.14. UPS & battery feed power supply mode
mode if H-1 failure
The above figure (7) indicates the source voltage from grid, fig (10) shows the D.C bus voltage
which will be 220 volts constant in all modes operation except in by pass power supply mode,
remaining figures (8),(9),(10),(11),(12) & (13) will shows the output current and voltage during
static by pass mode, UPS mode, battery power supply mode, Battery feed power supply mode,
Battery power feed & Battery supply mode if H-3 failure and UPS & battery feed power supply
mode mode if H-1 failure respectively.
CONCLUSION
In order to meet the present modern trend electricity demand and as well as to give additional
support to the smart grid, the proposed intelligent uninterruptable power supply will plays a very
important role, in view of this we are proposed the IUPS and analysed, the whole system by designed
the system with the help of Matlab Simulink toll and we are verified for the different modes of
operation. The unidirectional electricity providing UPS system can’t satisfy the need of the demand
of it anymore, “Green,” energy saving, modular, and IUPS system become the main development
trend. The proposed IUPS system not only can analyse all the basic functions of the conventional
UPS system, but also can fill the gap between the electrical power and the power grid and storage
battery and make it become a “Green” user to the power grid. By this we can easily achieve the
continuous power supply without interrupting and also it can be easily switched into different mode
depending of the need of application also can apply for type drive system and other so many
applications and ultimately it leads to the growth of the country economy and the whole system will
looks holistic manner.
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Ravi Angadi, S. Zabiullah, Ch. Jayavardhana Rao
Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences
www.ijetmas.com September 2014, Volume 2 Issue 4, ISSN 2349-4476
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